From the FAQ on the Homepage:

Internet Junkbuster Proxy TM is free privacy-enhancing software
that can be run on your PC or by your ISP or company. It blocks
requests for URLs (typically banner ads) that match its blockfile.
It also deletes unauthorized cookies and other unwanted identifying
header information that is exchanged between web servers and browsers.
These headers are not normally accessible to users (even though
they may contain information that's important to your privacy), but
with the Internet Junkbuster you can see almost anything you want
and control everything you're likely to need. You decide what's
junk.  Many people publish their blockfiles to help others get
started.
